Nitrile-producing method



Au8- 31 1943- R. H. PoT'rs NITRILE-PRODUCING METHOD Filed June 29, 1945 Patented Aug. 31, 194s 2,448,215 mma-raopucma mamon Ralph n. rota, Armour and tion oi' Illinois COMUN,

La Grange, Ill., signor to Chicago, Ill.,acorpora Application June 29, 1945, Serial No. 602,220

a claims. (ci. 2st-465.2)

This invention relates to a nitrile-producing method and apparatus, and is particularly useful in the manufacture of nitriles, etc., from fatty acids.

An object of the invention is to provide a method and apparatus in which a product considerablyr higher in nitrile content is produced, while at the ,same time eliminating the necessity of redistilling the .bottoms or residues, as required in prior practice. A further object is to provide apparatus and process in which pitch will be produced as a finished product without the necessity of redistillation as heretofore found necessary. A further object is to provide a continuous liquidphase process in whichstripped fatty acid residues are reacted with fresh or recycled ammonia and in which the ammonia vapors evolved are utilized for stripping incoming fatty acid charging stock. Other specific objects and advantages will appear as the specification proceeds.

The invention is illustrated in a preferred embodiment, by the accompanying drawing, which shows in elevation diagrammatical apparatus embodying my invention and illustrating my process.

In the illustration given, fatty acid charging stock is introduced through line i0 into the heater i i in which any suitable heating medium, such as, for example, Dowtherm, may be employed for drying the stock. Preferably, flow-control apparatus i0, which per se is of well-known construction, is employed to maintain a constant rate of iiow through line i0. From the heater, the fatty acids which have been preheated pass through line i2 to a reaction tower i 3 in which the fatty acids are brought into contact with ammonia and nitrile vapors. The reaction tower i3 is provided with an overhead outlet line i4 leading to the condenser i5. Nitrile vapors, ammonia, water of reaction, and some fatty acids will distill upwardly through the tower and be condensed in condenser I5. Part of the condensed material will pass through line I8 to the heater i9, while a portion of the material will pass as reflux through line i6 to the tower, forcing the higher boiling fatty acid material downwardly through the tower to the heater I1 at the base of the tower. The heater i1 shown in the drawing is of the Callandria type employing Dowtherm as a heating medium. Other types of heaters using any suitable heating medium may be employed. The heater I1 brings the material to a temperature suitable for liquid phase reaction of the fatty acids and ammonia (about 575-625 F. for most charging stocks). A residue withdrawal line 2h leads from 1 20v has similar tubes 30a.

2 the base of tower il and enters the upper portion of a second reaction tower 2i The tower I3 is provided with trays or pans, as'indicated in the drawing by dotted lines Il,

and gaseous ammonia passing upwardly in the tower cornes successively into contact with liquid fatty acids on these trays to complete the liquid phase reaction and produce the nitrile product. The ratio of nitriles to fatty acids becomes progressively greater toward the top of the tower.

As illustrated diagrammatically, means are provided for automatically maintaining a level of high boiling fatty acid residue in the lower portion of tower I2. Valve mechanism 22 is controlled by electric mechanism of wellknown.con struction (per se) actuated by a level control 23 in the lower portion of tower i3. By this means, a predetermined level is maintained in the tower.

Reaction tower 2i may be of any suitable construction. 'In the illustration given, it is shown provided with an overhead vapor line 24 through which ammonia, nitrile vapors, and fatty acids pass into the lower portion of the pool maintained in the base of tower i3. Heated ammonia is passed into the base of tower 2i through line 25.

A residual line 28 leads from the base of tower which may beV intermittent or continuous. InV

the structure shown, I provide a valve 21 which is electrically operated to control the withdrawal of pitch in accordance with a level control device 22 at the lower portion of tower 2 i.

Tower 2i may be provided with the trays 2lL indicated by dotted lines in the drawing. These trays contain a certain amount of liquid fatty acids, and the gaseous ammonia passing upwardly in large volume comes successively into contact with the liquid on each tray. The ammonia serves to carry the fatty acids upwardly, separating them from the pitch, and also reacts with the acidsto some extentto produce an appreciable amount of nitriles in this tower.

The material passing from condenser through line i8 preferably is heated to a temperature suitable for vapor phase reaction of the fatty ac lds and ammonia (600700 F. for most stocks) in heater i9 and is then passed through one of the catalyst chambers 29 and 30. Catalyst chamber 28 has tubes 29* in which is held a 'suitable dehydrating catalyst, such as nickel, and chamber The catalyst chambers may be of any suitable construction. They are shown each provided with heating lines 3i through which Dowtherm or other heating fluid may be passed into the chambers aboutthe tubes ZS'and 30B. Lines 32 may be employed for introdueing steam and air into the catalyst chambers for the purpose of regeneration of the catalyst,

and `valve-controlled vents 32B permit the escape i of steam and air. I

From "the catalyst chambers, thev material passes through line 33 into astripping tower 34 having bubble pans or plates with a series of vertically-spaced drawoff outlets 35. Water may be withdrawn, together with impurities, from one of the intermediate pans. while, if desired, an ammonia solution may be drawn off from one of the upper pans. The overhead vapors pass out through line 36 and are condensed in condenser 31, the condensate being returned through line 38 to the upper portion of the stripping tower.V

The uncondensed ammonia is returned through line 39 and may be reused by passing it through -line 40 and heater 4I from which it enters thel struction per se, and'which maintains a constant rate of flow through line 40. Heretofore it has been the practice to redlstill stripped fatty acid residues with the aid of steam to form a finished pitch product, this step being a separate operation. In the present process, the pitch is recovered as a finished product at the base of the second tower and without any further treatment, while at the same time an increase in nitrile content of the stripped vapors is accomplished in the second tower. A pool of high boiling fatty acid material is maintained in the base of the first tower, and it is into the lower portion of this pool that the evolved vapors from the second tower are introduced. Thus, the incoming fatty acid is first encountered in the reaction chamber I3 above the liquid pool by the gaseous ammonia from the second tower; then the stripped residue while in the pool at the base of the tower is again subjected to such vapors; and finally in the second tower the stripped material undergoes a further reaction and stripping operation. meeting in the base portion of the tower ihe fresh ammonia entering the tower. The entering ammonia passes into a pool of higher boiling fatty acid residue and pitch is substantially continuously withdrawn through the outlet pipe 2G. The towers I3 and 2| are preferably operated at atmospheric pressure or slightly above.

In the second tower 2|, the stripping action is unusually effective because the ratio of molecules of ammonia to molecules of fatty acid is very char-ply increased and therefore the partial pressure of the fatty acid is much lower, thus allowing it to distill at a lower boiling point. There is also more mechanical action as a result of the increased agitation. The chemica1 relationship is also improved because the mass effect of the large ratio :of ammonia to fatty acids in the second towerdrives the chemical reaction in the desired l direction toward nitrile formation.

While in the foregoing specification, I have set forth certain details of operation and specified certain apparatus, it -will be understood that such' details and apparatus structures are set forth for the purpose :of explaining the invention and the same may be varied widely by those skilled in the 4 art without departing from the spirit of my invention. y

Iclaim:

1. In a nitrile-producing process, the steps of maintaining two ammonia-fatty-acid reaction zones, passing fatty acids into the'iirst of said zones,'heatin 'g said acids in said zone toa liquid phase reaction temperature, contacting the same with ammonia dvapors evolved from the second of said zones; passing high boiling fatty acid residue from said first zone to saidfsecond zone, contacting the same in said second-zone with am,- monia vapors, and withdrawing the stripped high boiling residue as pitch from said secondzone.

2. In a nitrile-producing process, the steps of maintaining two ammonia-fatty-acid reaction zones, passing fatty acids into the first of said zones, contacting the same with nitrile-and ammonia vapors evolved from `the second of said zones, maintaining in said first zone a pool of high boiling fatty acid lmaterial, heating said pool to a liquid phase reaction temperature, passing material from said pool to said second zone, contacting the same in said second Zone with ammonia vapors, and withdrawing the stripped high boiling residue as pitch from said second zone.

3. In a nitrile-producing process, the steps of maintaining two ammonia-fatty-acid reaction zones, passing fatty acids into the first of said zones, heating said acids to aliquid phase reaction temperature. contacting said acids with ammonia vapors evolved from the second of said zones, passing high boiling fatty acid residue from said iirst zone to said second zone, maintaining a pool of high boiling fatty acid residue in said second zone, introducing ammonia into said pool of residue, and withdrawing stripped high boiling residue as pitchfrorn said second zone.

4. In a nitrile-producing process, the steps of maintaining two ammonia-fatty-acid reaction zones, passing fatty aci-ds into the first of said zones, heating said acids to a liquid phase revapors, maintainingv a pool of high boiling fattyV acid residue in said second zone, introducing ammonia into said pool, and withdrawing stripped high boiling residue as pitch from said pool in said second zone. l

5. In a nitrile-producing process, the steps of maintainingtwo ammonia-fatty-acid reaction zones, passing fatty acids into the first of said zones, heating said fatty acids to a liquid phase reaction temperature, contacting the same with ammonia vapors evolved from the second of said zones, passing high boiling fatty acid residue from said first zone to said second zone, Withdrawing nitrile, ammonia, and water vapors from said rst zone, separating the ammonia, returning the ammonia to said second zone, contacting the residue in said second zone with said returned ammonia, and withdrawing the stripped highboiling residue as pitch from said second zone.

6. In a nitrile-producing process, the steps of maintaining two ammonia-fatty-acid reaction zones, passing fatty acids into the first of said zones, heating said fatty acids to a liquid phase reaction temperature, .contacting the same with ammonia vapors evolved from the second of said zones, passing high .boiling fatty acid residue from said first zone to said second zone, contacting the same in said second zone with ammonia vapors, maintaining a pool of high boiling fatty acid residue in said second zone, withdrawing nitrile, ammonia, and water vapors from said first zone, separating the ammonia, returning the ammoniaat elevated temperatures to the pool in said second zone, contacting the residue in said second zone with said returned ammonia, and withdrawing the stripped high-boiling residue as pitch from said second zone.

'7. In a liquid phase nitrile-producing process, the steps of maintaining two ammonia-fattyacid reaction zones, passing fatty acids into the rst of said zones, heating said acids therein to liquid phase reaction temperature, contacting the same with ammonia vapors evolved from the second of said zones, passing high boiling fatty acid residue from said first zone to said second zone, introducing into said second zone in contact with said fatty acid residue, the bulk of the ammonia required for the reaction in the two zones, contacting said high-boiling fatty acid residue in said second zone with said ammonia to strip said high-boiling fatty acid residue, and withdrawing the stripped high boiling residue from said second zone.

8. In a nitrile-producing process, the steps of maintaining two ammonia-fatty-acid reaction zones, passing fatty acids into the first of said zones, heating said acids in said zone to aliquid phase reaction temperature, contacting the same with ammonia vapors evolved from the second of REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,225,226 Doherty May 8, 1917 1,953,939 Jones Apr. 10, 1934 1,991,955 Ralston Feb. 19, 1935 1,997,675 Bahlke et al. Apr. 16, 1935 2,033,536 Ralston et al. Mar. 10, 1936 2,033,537 Ralston et al. Mar. 10, 1936 2,042,729 Ralston et al. June 2, 1936 2,061,314 Ralston et al Nov. 17, 1936 2,076,126 Guinot Apr. 6, 1937 2,177,619 Nicodemus et al. Oct. 24, 1939 2,205,076 Wortz June 18, 1940 2,229,219 Oxley et al. Jan. 21, 1941 2,314,894 Potts et a1 Mar. 30, 1943 2,335,441 Pearson et al Nov. 30, 1943 OTHER REFERENCES 

